1. Field of the Invention
The invention relates to a battery pack management method for HEV and EV, and more particularly to a battery pack management method for HEV and EV capable of properly controlling a battery pack connection circuit provided between a battery pack and a power conversion circuit through a battery management system (BMS) of the battery pack or a vehicle control device so that a smoothing capacitor or related devices of the power conversion circuit can be prevented from being damaged in advance when surge current is applied to the power conversion circuit of a vehicle motor unit from the battery pack in starting the vehicle with a start key, and notifying a driver of a diagnosis result through warning means when over-current flows to a pre-charge resistor of the battery pack connection circuit or a pre-charge relay of the battery pack connection circuit is turned off due to over-current or over-voltage during the driving, thereby contributing to a safety drive of the vehicle.
2. Description of the Prior Art
In general, a vehicle using gasoline, diesel oil or LPG as fuel generates a large quantity of harmful exhaust gas to pollute the atmosphere and to induce the global warming, thereby causing damages to the mankind as well as the global environment. Accordingly, in order to solve the problems, it has been actively conducted researches on a hybrid electric vehicle (HEV) having a little exhaust gas or electric vehicle (EV) having no exhaust gas, in most related industries.
The HEV is driven with a driving motor, which uses electricity supplied from a main battery via a power conversion circuit as a driving source, as well as an internal combustion engine using the gasoline, diesel oil or LPG as the fuel. Further, the HEV is controlled so that the fuel efficiency of the vehicle is improved to the utmost in correspondence with each driving situation.
The driving motor of the HEV is converted into a generation mode from a driving mode though control of a hybrid control unit (HCU) when the vehicle is braked or decelerated. At this time, the main battery is charged case-by-case by the electric energy generated from a generator (or driving motor) under control of a battery management system (BMS) connected to the HCU. The currents applied to the main battery from the generator are different and discontinuous depending on the driving situations of the vehicle.
In the mean time, as shown in FIG. 1, a battery pack connection circuit 1 is provided between the power conversion circuit and the main battery for the driving motor. The battery pack connection circuit 1 applies a charge current to the main battery from the driving motor (or generator) under generation mode and applies a driving current to the driving motor from the main battery under driving mode, so that the vehicle is driven by the electric energy.
To the battery pack connection circuit 1 are respectively connected a HV (−) lead and a HV (+) lead for applying the current to the power conversion circuit from the main battery, in a predetermined pattern. To an input terminal of the HV (+) lead is connected a pre-charge resistor 2 for limiting a surge over-current applied to the power conversion circuit from the main battery when the vehicle is started. In addition, a pre-charge relay 3 for high-voltage and a relay 4 for high-voltage main power supply capable of controlling the over-current are respectively connected between the pre-charge resistor and an output terminal through different routes. In the mean time, the HV (−) lead is provided with a separate relay 4a for main power supply capable of controlling the over-current applied to the driving motor from the main battery.
The relays 4, 4a and the pre-charge relay 3 are respectively provided with condensers connected through a control lead applied with 12V current from the main battery. The respective condensers are capable of turning on/off the corresponding relays 3, 4, 4a under control of the BMS. The current flowing through the output terminal of the battery pack connection circuit is measured by a Hall sensor or transformer provided to the output terminal of the HV (−) lead (see FIGS. 1 and 2).
However, the battery back connection circuit of the conventional HEV or EV is not provided with warning means. Accordingly, even though the over-current flows or the over-voltage is applied to the high-voltage pre-charge resistor of the battery pack connection circuit and the pre-charge relay is under ON state, a driver cannot properly cope with the emergency situation. Further, the over-current flows to the power conversion circuit of the driving motor in the vehicle, thereby causing the smoothing capacitor to be damaged.